The R165 at Galbolie, 3 km west-north-west of the town of Bailieborough

For most of its length the R165 runs in a west-by-northwesterly course from the N2 at Blakestown Cross, 3 km south of Ardee in County Louth, through Drumconrath (alias Drumcondra) in County Meath and Kingscourt and Bailieborough in County Cavan to the N3 at Knockanoark. Here, it turns it turns north and northeastward for its final 11.5 km run through Stradone before ending on the R188 at Drumnagran, 1.5 km west of Tullyvin.